diff mbox

[RFC] ipv6: allow rejecting with "source address failed policy"

Message ID 1370270708-24398-1-git-send-email-jogo@openwrt.org
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Jonas Gorski June 3, 2013, 2:45 p.m. UTC 
RFC6204 L-14 requires rejecting traffic from invalid addresses with
ICMPv6 Destination Unreachable, Code 5 (Source address failed ingress/
egress policy) on the LAN side, so add an appropriate rule for that.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
---
Since I'm a total noob in regard to the net subsystem, this is a RFC
patch for now. The things that bug me:

Is -EPERM a sensible error message?

Do I need one at all?

Is adding its handling to IPv4 necessary? It seems to me the fib_*
need to cover all RTN_* values.

Because I don't expect this patch to survive the review I did not send
any userspace patches yet.

Regards,
Jonas

 include/net/netns/ipv6.h       |    1 +
 include/uapi/linux/fib_rules.h |    4 +++
 include/uapi/linux/icmpv6.h    |    1 +
 include/uapi/linux/rtnetlink.h |    1 +
 net/ipv4/fib_rules.c           |    4 +++
 net/ipv4/fib_semantics.c       |    4 +++
 net/ipv4/fib_trie.c            |    1 +
 net/ipv4/ipmr.c                |    1 +
 net/ipv6/fib6_rules.c          |    3 +++
 net/ipv6/ip6mr.c               |    2 ++
 net/ipv6/route.c               |   57 +++++++++++++++++++++++++++++++++++++++-
 11 files changed, 78 insertions(+), 1 deletion(-)

Comments

David Miller June 7, 2013, 10:27 p.m. UTC | #1 
From: Jonas Gorski <jogo@openwrt.org>
Date: Mon,  3 Jun 2013 16:45:08 +0200

> RFC6204 L-14 requires rejecting traffic from invalid addresses with
> ICMPv6 Destination Unreachable, Code 5 (Source address failed ingress/
> egress policy) on the LAN side, so add an appropriate rule for that.
> 
> Signed-off-by: Jonas Gorski <jogo@openwrt.org>

I don't see the point of this, there is no difference from the
existing PROHIBIT other than the error code.  Everything that needs to
be expressed can be done using PROHIBIT.

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Jonas Gorski June 7, 2013, 10:40 p.m. UTC | #2 
On Fri, 07 Jun 2013 15:27:30 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> From: Jonas Gorski <jogo@openwrt.org>
> Date: Mon,  3 Jun 2013 16:45:08 +0200
> 
> > RFC6204 L-14 requires rejecting traffic from invalid addresses with
> > ICMPv6 Destination Unreachable, Code 5 (Source address failed
> > ingress/ egress policy) on the LAN side, so add an appropriate rule
> > for that.
> > 
> > Signed-off-by: Jonas Gorski <jogo@openwrt.org>
> 
> I don't see the point of this, there is no difference from the
> existing PROHIBIT other than the error code.  Everything that needs to
> be expressed can be done using PROHIBIT.
> 

There is a semantic difference. PROHIBIT says the *destination*
address is not allowed, so trying again is pointless.

This one says the while the destination is allowed, the *source*
address is not allowed, and a different source address should be used.
So probably -EAGAIN would be the right error code in that case.
"POLICY_FAILED" is maybe a wrong abbreviation, but the full name is
quite long (I'm open for suggestions).

Of course maybe handling of this kind of message should be added, too;
which should trigger the source address selection to chose a different
one.

Unless you say I can change the ICMPv6 Destination Unreached Code used
through appropriate rules, then this might be redundant.


Regards
Jonas



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diff mbox

Patch

diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 005e2c2..a6a1df4 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -55,6 +55,7 @@  struct netns_ipv6 {
 	unsigned long		 ip6_rt_last_gc;
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	struct rt6_info         *ip6_prohibit_entry;
+	struct rt6_info		*ip6_failed_policy_entry;
 	struct rt6_info         *ip6_blk_hole_entry;
 	struct fib6_table       *fib6_local_tbl;
 	struct fib_rules_ops    *fib6_rules_ops;
diff --git a/include/uapi/linux/fib_rules.h b/include/uapi/linux/fib_rules.h
index 51da65b..1429852 100644
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -64,6 +64,10 @@  enum {
 	FR_ACT_BLACKHOLE,	/* Drop without notification */
 	FR_ACT_UNREACHABLE,	/* Drop with ENETUNREACH */
 	FR_ACT_PROHIBIT,	/* Drop with EACCES */
+	FR_ACT_RES9,
+	FR_ACT_RES10,
+	FR_ACT_RES11,
+	FR_ACT_FAILED_POLICY,	/* Drop with EPERM */
 	__FR_ACT_MAX,
 };
 
diff --git a/include/uapi/linux/icmpv6.h b/include/uapi/linux/icmpv6.h
index e0133c7..dabfa1a 100644
--- a/include/uapi/linux/icmpv6.h
+++ b/include/uapi/linux/icmpv6.h
@@ -115,6 +115,7 @@  struct icmp6hdr {
 #define ICMPV6_NOT_NEIGHBOUR		2
 #define ICMPV6_ADDR_UNREACH		3
 #define ICMPV6_PORT_UNREACH		4
+#define ICMPV6_FAILED_POLICY		5
 
 /*
  *	Codes for Time Exceeded
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 7a2144e..8f643f1 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -203,6 +203,7 @@  enum {
 	RTN_THROW,		/* Not in this table		*/
 	RTN_NAT,		/* Translate this address	*/
 	RTN_XRESOLVE,		/* Use external resolver	*/
+	RTN_FAILED_POLICY,	/* Failed ingress/egress policy */
 	__RTN_MAX
 };
 
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 26aa65d..2f66341 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -84,6 +84,10 @@  static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
 		err = -EACCES;
 		goto errout;
 
+	case FR_ACT_FAILED_POLICY:
+		err = -EPERM;
+		goto errout;
+
 	case FR_ACT_BLACKHOLE:
 	default:
 		err = -EINVAL;
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 8f6cb7a..dbae75d 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -138,6 +138,10 @@  const struct fib_prop fib_props[RTN_MAX + 1] = {
 		.error	= -EINVAL,
 		.scope	= RT_SCOPE_NOWHERE,
 	},
+	[RTN_FAILED_POLICY] = {
+		.error	= -EPERM,
+		.scope	= RT_SCOPE_UNIVERSE,
+	},
 };
 
 static void rt_fibinfo_free(struct rtable __rcu **rtp)
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 49616fe..e2845bd 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2334,6 +2334,7 @@  static const char *const rtn_type_names[__RTN_MAX] = {
 	[RTN_THROW] = "THROW",
 	[RTN_NAT] = "NAT",
 	[RTN_XRESOLVE] = "XRESOLVE",
+	[RTN_FAILED_POLICY] = "FAILED_POLICY",
 };
 
 static inline const char *rtn_type(char *buf, size_t len, unsigned int t)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index df97f0a..2bd33cc 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -181,6 +181,7 @@  static int ipmr_rule_action(struct fib_rule *rule, struct flowi *flp,
 	case FR_ACT_UNREACHABLE:
 		return -ENETUNREACH;
 	case FR_ACT_PROHIBIT:
+	case FR_ACT_FAILED_POLICY:
 		return -EACCES;
 	case FR_ACT_BLACKHOLE:
 	default:
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 2e1a432..c4413b2 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -69,6 +69,9 @@  static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 	case FR_ACT_PROHIBIT:
 		rt = net->ipv6.ip6_prohibit_entry;
 		goto discard_pkt;
+	case FR_ACT_FAILED_POLICY:
+		rt = net->ipv6.ip6_failed_policy_entry;
+		goto discard_pkt;
 	}
 
 	table = fib6_get_table(net, rule->table);
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 583e8d4..1e524da 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -166,6 +166,8 @@  static int ip6mr_rule_action(struct fib_rule *rule, struct flowi *flp,
 		return -ENETUNREACH;
 	case FR_ACT_PROHIBIT:
 		return -EACCES;
+	case FR_ACT_FAILED_POLICY:
+		return -EPERM;
 	case FR_ACT_BLACKHOLE:
 	default:
 		return -EINVAL;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 2b87418..864f5fe 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -245,6 +245,24 @@  static const struct rt6_info ip6_prohibit_entry_template = {
 	.rt6i_ref	= ATOMIC_INIT(1),
 };
 
+static int ip6_pkt_failed_policy(struct sk_buff *skb);
+static int ip6_pkt_failed_policy_out(struct sk_buff *skb);
+
+static const struct rt6_info ip6_failed_policy_entry_template = {
+	.dst = {
+		.__refcnt	= ATOMIC_INIT(1),
+		.__use		= 1,
+		.obsolete	= DST_OBSOLETE_FORCE_CHK,
+		.error		= -EPERM,
+		.input		= ip6_pkt_failed_policy,
+		.output		= ip6_pkt_failed_policy_out,
+	},
+	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
+	.rt6i_protocol	= RTPROT_KERNEL,
+	.rt6i_metric	= ~(u32) 0,
+	.rt6i_ref	= ATOMIC_INIT(1),
+};
+
 static const struct rt6_info ip6_blk_hole_entry_template = {
 	.dst = {
 		.__refcnt	= ATOMIC_INIT(1),
@@ -1459,6 +1477,9 @@  int ip6_route_add(struct fib6_config *cfg)
 		case RTN_THROW:
 			rt->dst.error = -EAGAIN;
 			break;
+		case RTN_FAILED_POLICY:
+			rt->dst.error = -EPERM;
+			break;
 		default:
 			rt->dst.error = -ENETUNREACH;
 			break;
@@ -2035,6 +2056,17 @@  static int ip6_pkt_prohibit_out(struct sk_buff *skb)
 	return ip6_pkt_drop(skb, ICMPV6_ADM_PROHIBITED, IPSTATS_MIB_OUTNOROUTES);
 }
 
+static int ip6_pkt_failed_policy(struct sk_buff *skb)
+{
+	return ip6_pkt_drop(skb, ICMPV6_FAILED_POLICY, IPSTATS_MIB_INNOROUTES);
+}
+
+static int ip6_pkt_failed_policy_out(struct sk_buff *skb)
+{
+	skb->dev = skb_dst(skb)->dev;
+	return ip6_pkt_drop(skb, ICMPV6_FAILED_POLICY, IPSTATS_MIB_OUTNOROUTES);
+}
+
 #endif
 
 /*
@@ -2240,7 +2272,8 @@  static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (rtm->rtm_type == RTN_UNREACHABLE ||
 	    rtm->rtm_type == RTN_BLACKHOLE ||
 	    rtm->rtm_type == RTN_PROHIBIT ||
-	    rtm->rtm_type == RTN_THROW)
+	    rtm->rtm_type == RTN_THROW ||
+	    rtm->rtm_type == RTN_FAILED_POLICY)
 		cfg->fc_flags |= RTF_REJECT;
 
 	if (rtm->rtm_type == RTN_LOCAL)
@@ -2442,6 +2475,9 @@  static int rt6_fill_node(struct net *net,
 		case -EACCES:
 			rtm->rtm_type = RTN_PROHIBIT;
 			break;
+		case -EPERM:
+			rtm->rtm_type = RTN_FAILED_POLICY;
+			break;
 		case -EAGAIN:
 			rtm->rtm_type = RTN_THROW;
 			break;
@@ -2692,6 +2728,8 @@  static int ip6_route_dev_notify(struct notifier_block *this,
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 		net->ipv6.ip6_prohibit_entry->dst.dev = dev;
 		net->ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(dev);
+		net->ipv6.ip6_failed_policy_entry->dst.dev = dev;
+		net->ipv6.ip6_failed_policy_entry->rt6i_idev = in6_dev_get(dev);
 		net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
 		net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
 #endif
@@ -2952,6 +2990,17 @@  static int __net_init ip6_route_net_init(struct net *net)
 	net->ipv6.ip6_blk_hole_entry->dst.ops = &net->ipv6.ip6_dst_ops;
 	dst_init_metrics(&net->ipv6.ip6_blk_hole_entry->dst,
 			 ip6_template_metrics, true);
+
+	net->ipv6.ip6_failed_policy_entry =
+		kmemdup(&ip6_failed_policy_entry_template,
+			sizeof(*net->ipv6.ip6_failed_policy_entry), GFP_KERNEL);
+	if (!net->ipv6.ip6_failed_policy_entry)
+		goto out_ip6_blk_hole_entry;
+	net->ipv6.ip6_failed_policy_entry->dst.path =
+		(struct dst_entry *)net->ipv6.ip6_failed_policy_entry;
+	net->ipv6.ip6_failed_policy_entry->dst.ops = &net->ipv6.ip6_dst_ops;
+	dst_init_metrics(&net->ipv6.ip6_failed_policy_entry->dst,
+			 ip6_template_metrics, true);
 #endif
 
 	net->ipv6.sysctl.flush_delay = 0;
@@ -2970,6 +3019,8 @@  out:
 	return ret;
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
+out_ip6_blk_hole_entry:
+	kfree(net->ipv6.ip6_blk_hole_entry);
 out_ip6_prohibit_entry:
 	kfree(net->ipv6.ip6_prohibit_entry);
 out_ip6_null_entry:
@@ -2987,6 +3038,7 @@  static void __net_exit ip6_route_net_exit(struct net *net)
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	kfree(net->ipv6.ip6_prohibit_entry);
 	kfree(net->ipv6.ip6_blk_hole_entry);
+	kfree(net->ipv6.ip6_failed_policy_entry);
 #endif
 	dst_entries_destroy(&net->ipv6.ip6_dst_ops);
 }
@@ -3083,6 +3135,9 @@  int __init ip6_route_init(void)
 	init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
 	init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
 	init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+	init_net.ipv6.ip6_failed_policy_entry->dst.dev = init_net.loopback_dev;
+	init_net.ipv6.ip6_failed_policy_entry->rt6i_idev =
+		in6_dev_get(init_net.loopback_dev);
   #endif
 	ret = fib6_init();
 	if (ret)